During recent years, huge efforts have been made to establish digital libraries, in a variety of media, offered from a variety of sources, and intended for a variety of professional and private user communities. As digital data collections proliferate, problems of resource selection and data fusion become major issues. Traditional search engines, even the best ones, are unable to provide access to the hidden web of information that is only available via digital library search interfaces.Originating from the SIGIR 2003 Workshop on Distributed Information Retrieval, held in Toronto, Canada in August 2003, this book presents extended and revised workshop papers as well as several invited papers on the topic to round off coverage of the core issues. The papers are devoted to recent research on the design and implementation of methods and tools for resource discovery, resource description, resource selection, data fusion, and user interaction.